You need to follow this guidance if you are examining the potential or current effect of burials in a cemetery or individually, as part of a risk assessment. You will need to undertake a risk assessment, for example:

as part of a planning application or condition

when altering existing facilities

following a pollution incident

when ongoing environmental management of the site is needed, for example disposal of grey water

These principles also apply to pet cemeteries and the emergency burial of animal carcasses.

You need to submit your risk assessment to the Environment Agency or your local authority, depending on who has requested it. Your assessment will need to be approved before you begin or continue your activity.

microbiological contaminants will not endanger water resources or supplies

You should use a tiered approach for risk assessments. The cost, time and effort in undertaking an assessment is proportional to the effort or measures required to make the risks from the activity acceptable.

Tier 1 risk assessment: risk screening

For a tier 1 assessment, you need to do a desk study and a qualitative risk assessment. Each risk is ranked using a scoring system to prioritise those of most concern. The overall risk of the proposal can then be assessed as low, medium or high. For high and medium risks you need to do a more detailed tier 2 or 3 risk assessment.

Tier 2 and 3 assessments: detailed risk assessments

For tier 2 and 3 assessments you need to build on the information you gathered in your tier 1 assessment and refine your conceptual model.

If your risk assessment shows pollution or a risk of pollution you need to work with your local authority and the Environment Agency on how to address this. At existing cemeteries you will have to stop burials until you have an agreed plan of action.

Tier 2 and 3 minimum risk assessment requirements

For tier 2 and 3 assessments you need to supply the following minimum information.

Site description

Your risk assessment must show for:

tier 2, a local survey to supplement Ordnance Survey maps

tier 3, an accurate site survey based on location, area and topography – mark any landscaping included in the proposal

Number, type and sequence of burials

Your risk assessment must show for:

tier 2, projections on which annual numbers are based should be available with supporting data and explanation

tier 3, use the tier 2 projections and a plan of the proposed sequence of burial area usage with indication of expected progression over time

You may also need to carry out monitoring outside the burial boundary. For example, if burials are close to the perimeter of cemetery grounds.

You need to carry out monitoring to:

define the baseline water quality and physical conditions in surrounding groundwater and surface waters before development

identify all vulnerable receptors and help identify potential pathways

provide an early warning of adverse environmental impacts

If monitoring identifies groundwater pollution, you must stop burials and carry out further investigations to find out the cause. You must also contact the Environment Agency who may require you to take action to sort out the pollution before burials can start again. Remember this applies to human and pet cemeteries.

Minimum monitoring requirements

You may need to consider what parameters you’re monitoring on a site-specific basis. For example, you may need to include formaldehyde, organics, hazardous substances and bacterial indicators.

Where you need to monitor groundwater, you must meet the following minimum requirements for pre-development and ongoing burials.

Minimum number of boreholes

You should have at least 1 borehole up-gradient of the boundary of the site and 2 boreholes down-gradient of the boundary of the site. The down-gradient boreholes should be spaced no more than 100 metres apart. You should work out the groundwater flow direction from your monitoring boreholes.

Minimum borehole monitoring period

You should monitor:

12 months before site development

for a period of 3 years after first interment

For higher risk sites, the Environment Agency may require an increase in the frequency of monitoring, both prior to development and longer term. This will depend on the sensitivity of the site and the results of the monitoring and can be reviewed accordingly.

Surface water monitoring points

For surface waters that are at risk you should have 1 monitoring point upstream and 1 downstream. These should be monitored on a monthly basis.

Baseline conditions

The minimum frequency for monitoring of baseline conditions and the monitoring suite (the determinands) prior to development is either quarterly or 6 monthly.

You may also need to increase the frequency of monitoring for higher risk sites or decrease it to annual monitoring if monitoring shows stable conditions.

Calculate your site’s pollutant release

You can use the following information to calculate the potential release of pollutants from your site.

Composition of the human body:

Composition

% weight

Water

64

Protein

20

Carbohydrate

1

Mineral Salts

5

Fat

10

Element components:

Elemental Component

% dry weight

Carbon

80.6

Nitrogen

9.2

Calcium

5.6

Magnesium

0.1

Sodium

0.3

Potassium

0.7

Phosphorus

2.5

Sulphur

0.7

Chloride

0.3

Iron

«0.01

Heavy Metals

Trace

Rates of release

Micro-organisms are mainly responsible for the breakdown of human remains. The rate of decay depends on the extent of microbial growth and activity. The proportions of degradable matter in a human body are:

readily degradable – 60%

moderately degradable – 15%

slowly degradable – 20%

inert (non-degradable) – 5%

The slowly degradable and inert rates assume that mineral salts (ashes) form a final stable residue. The slowly degradable component of bones may be considered for practical purposes.

burial practice – depth of burial and coffin construction control the ease with which micro-organisms and other invertebrates and vertebrates may gain access

Pathogens (mainly micro-organisms such as a virus or bacteria that cause disease) may also be present. They will die off naturally and rapidly reduce in concentration with increasing distance from the grave. Physical conditions like temperature, moisture content, organic content and soil pH will also affect their survival time.

There is also the potential, depending on the natural soil characteristics, for an increased soil pH resulting from a high proportion of calcium. This may impact upon degradation rates and micro-organism activity.

Estimates suggest that more than half the pollutant total leaches within the first year and halves year-on-year after that. Less than 0.1% of the original pollutant total may remain after 10 years.

Potential pollutant release (kg) from a single 70kg burial

Year

Total organic carbon

Ammonium

Calcium

Magnesium

Sodium

1

6.00

0.87

0.56

0.010

0.050

2

3.00

0.44

0.28

0.005

0.025

3

1.50

0.22

0.14

0.003

0.013

10

0.01

<0.01

<0.01

<0.001

<0.001

Year

Potassium

Phosphorus

Sulphate

Chloride

Iron

1

0.070

0.250

0.210

0.048

0.020

2

0.035

0.125

0.110

0.024

0.010

3

0.018

0.063

0.054

0.012

0.005

10

<0.001

<0.001

<0.001

<0.001

<0.001

Typical infiltration rates

The time it takes to flush pollutants from the buried body relates directly to effective rainfall and the infiltration rate through the soil and grave.

Estimate the possible average composition of effluent reaching the water table beneath the burial ground by dividing the pollutant release by the total annual infiltration.

This table gives an estimate of water infiltration (litres per year) through a typical grave plot.

Surface cover

Infiltration from grass surrounds

Infiltration from surface

Total annual infiltration

Chippings

2,000

750

2,750

Grass

2,000

500

2,500

Tress/shrubs (green burial)

2,600

250

2,850

This table is based on a mean annual rainfall of 650mm and typical evapotranspiration losses. Each grave and surrounding area is considered to be centred on:

5.06 metres squared for a typical municipal cemetery with a grave density of 1976 per hectare

6.32 metres squared for green burial sites with a grave density of 1580 per hectare

Green burial sites

Green burial sites usually have more rapid decay rates compared with conventional cemeteries because of:

relatively shallow depth of burial

biodegradable nature of the coffins or shrouds

lack of embalming fluids

You will need to consider infiltration rates, and adjust your calculations accordingly when carrying out your risk assessment. Infiltration rates may be lower on such sites due to increased evapotranspiration by trees and shrubs.

You should tailor the monitoring to suit products of aerobic decay processes such as nitrate and sulphate. This is because green burials are less polluting than anaerobic decay and for example, don’t usually include formaldehyde.

Attenuation of pollutants from burial sites

Pollutants from a burial site may migrate into the:

soil zone surrounding the burial

unsaturated zone of the underlying aquifer

saturated zone of the aquifer

Where there are shallow soil zones or deep graves, burials will affect the unsaturated zone directly.

Following burial the breakdown by the main processes of attenuation are summarised as:

in the soil zone, intense chemical and biochemical degradation, filtration and sorption takes place

in the unsaturated zone, sorption and filtration continue but there is reduced chemical and biochemical degradation

in the saturated zone, dilution and dispersion dominate – the extent of filtration is dependent on the nature of the aquifer, and chemical reactions dependent on the groundwater chemistry

Soils have complex content, with the potential for intense biochemical reactions, meaning contaminants may change while passing through them. Unless there is waterlogging, air access is generally good and this encourages rapid oxidation of pollutants.

Below the soil, in the unsaturated zone, less chemical and biological activity takes place. Oxygen diffusion from the surface is low and low oxygen (anoxic) conditions may develop. However, chemical and biochemical reactions may continue to attenuate pollutants. Filtration and sorption may continue to de-mobilise particulates and some dissolved pollutants.

The potential for the aquifer matrix to remove micro-organisms and pathogens by filtration depends on the nature of the matrix. Where the major route for groundwater flow is through a porous intergranular matrix, like sandstone aquifers, there is a high filtration potential.

Conversely, aquifers where fractures are the main flow route, like chalk aquifers, offer limited potential for filtration.

Transport of micro-organisms and pathogens

The transport of micro-organisms and pathogens in groundwater depends on their size, shape and their means of being transported through the aquifer.

Water abstracted from a shallow depth has a shorter travel time within the aquifer. Therefore it is more likely to be at risk of transporting micro-organisms and pathogens than water abstracted from a greater depth, which has a longer residence time.

Because of the short travel time, many springs and shallow wells are more vulnerable to microbial pollution problems than deep wells or boreholes.

21 August 2017
1. You will need to do a risk assessment for on-going environmental management, for example grey water disposal.
2. If you dispose of water at a human burial site then you must check if you need an environmental permit for that activity.

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